The most common corrective surgery for chronic sinusitis is functional endoscopic sinus surgery (FESS). In FESS, an endoscope is inserted into the nose and, under visualization through the endoscope, the surgeon may remove diseased or hypertrophic tissue or bone and may enlarge the ostia of the sinuses to restore normal drainage of the sinuses. FESS procedures can be effective in the treatment of sinusitis and for the removal of tumors, polyps and other aberrant growths from the nose.
The surgical treatment of diseases of the frontal sinuses presents unique postsurgical management issues due to the potential for formation of scar tissue, synachiae, or osteogenesis in the surgically altered frontal outflow tract. Thus, in order to maintain patency during the postsurgical period, stents are sometimes placed in the frontal outflow tract. Typically, it is intended for stents to remain in the frontal outflow tract for at least 1-8 weeks following FESS for treatment of frontal sinusitis and possibly as long as 6-12 months following surgeries for correction of frontal outflow tract stenosis.
Various types of makeshift stents have been used for this purpose, including segments of silicone drainage catheters, rolled silicone sheeting, segments of Foley catheters and Dacron materials. Also, the Freeman™ Frontal Sinus Stent is commercially available from InHealth Technologies, Inc., Carpinteria, California. The Freeman™ stent comprises a silicon tube that has flanges on either end to retain the stent within the frontal outflow tract for a desired period of time following surgery. In some cases, surgeons use gel like materials to form a “stent” in situ. One example of such material is the MeroPack™ Bioresorbable Nasal Dressing and Sinus Stent available from Medtronic ENT, Inc., Jacksonville, Fla. The MeroPack™ material consists of 80 percent esterified hyaluronic acid and 20 percent collagen. This material is inserted while in its dry state and, upon hydration, swells to 1.0 cm diameter in about six seconds. When in its hydrated state, this material is a biocompatible, muco-adhesive gel.
Some investigators have proposed the use of frontal sinus spacers or sheaths that elute drugs to facilitate healing in addition to performing the usual stenting function. For example, United States Patent Application Publication 2004/0116958A1 (Gopferich et al.) describes a tubular sheath or “spacer” formed of biodegradable or non-biodegradable polymer that, prior to insertion in the frontal outflow tract, is loaded with a controlled amount of an active substance, such as a corticosteroid or anti-proliferative agent. After surgery to create a fenestration in a frontal sinus as been performed, the sheath (which has been preloaded with the active substance) is inserted into the surgically created fenestration where it a) deters closure of the surgically created fenestration, b) serves as a conduit to facilitate drainage from the sinus and d) delivers the active substance. In some embodiments, the sheath is formed of multiple layers of polymeric material, one or more of which is/are loaded with the active substance and one or more of which is/are free of the active substance. In other embodiments, the sheath has a “hollow body” which forms a reservoir system wherein the active substance is contained and a membrane which controls the release of the active substance from the reservoir. In some embodiments, the sheath may be anchored by causing the end of the sheath that extends into the sinus to swell or otherwise enlarge.
To date, the use of stents and spacers in relation to nose and sinus surgery has been largely limited to placement in the frontal outflow tract following frontal sinus surgery. However, as new devices and methods become available for the treatment of other types of nasal and sinus disorders, there will likely be a need for intranasal or sinus spacers and stents (with or without drug eluting capabilities) suitable for placement at various locations lot limited to the frontal outflow tract.
For example, the ethmoid air cells are anatomical cavities that do not have native ostia or openings into the nasal cavity. In the prior art, diseased ethmoid air cells have sometimes been treated by a procedure known as an ethmoidectomy wherein a man made passageway is formed between the interiors of the ethmoid air cells and the nasal cavity. Stenting and/or delivery of drugs or other therapeutic substances into these man made ethmoidectomy passageways has been, in at least some cases, been desirable. To accomplish this, strips of gauze soaked with medication may be pushed into the man made opening and later extracted. Also, in this regard, U.S. Pat. No. 6,543,452 (Lavigne) describes a nasal intubation device that comprises a flexible tube having a flanged distal tip whereon the flanges generally from an arrow shape. The distal tip of this device is capable or penetrating through tissue (e.g., through the ethmoid bulla) to a desired position (e.g., within the ethmoid air cells). Openings are formed in a distal portion of the intubation device so that medication (e.g., a typical steroid) injected through the flexible tube will flow out of the tube into contact with the adjacent area (e.g., the diseased ethmoid air cells). In some cases, a cannula-trocar may be initially inserted and the nasal intubation device may then be advanced through that cannula-trocar. Also, European Patent Publication EP0624349 (Milewski) describes a balloon-tipped catheter having an anatomically shaped balloon which may be inserted through a surgically created opening into a body cavity (e.g., frontal sinus or ethmoid cell) and inflated to create a tamponade by being shaped to suit the anatomical shape of the cavity.
Also, in the future, placement of a drug eluting or non-drug eluting stents or spacer devices may also be desirable in the treatment of otitis media or inflammation of the middle ear. Most cases of otitis media are associated with some degree of Eustachian tube dysfunction. Because air cannot adequately pass through the Eustachian tube into the middle ear, negative pressure can be created within the middle ear. This negative pressure may essentially pull or draw fluid out of the lining of the middle ear/mastoid, thereby resulting in an accumulation of fluid in the middle ear behind the eardrum. In some cases, fluid that accumulates within the middle ear can become infected. Several types of otitis have been identified. Serous otitis typically results from a fairly sudden obstruction of the Eustachian tube and is characterized by the collection of generally thin, clear fluid in the middle ear and mastoid. If this fluid does not clear within a few weeks, it is considered chronic serous otitis. Secretory otitis typically occurs in small children and is characterized by the collection of a thick fluid in the middle ear and mastoid. This thick fluid contains muccoid material that has been secreted by the mucous glands of the middle ear and also contains enzymes that can damage the small bones and other tissues of the middle ear. If left untreated, these enzymes can erode the bones enough to cause permanent hearing loss. Acute otitis media is characterized by the accumulation of pus in the middle ear and typically occurs in patients who have active respiratory infections which result in an abrupt obstruction of the Eustachian tube at the same time as infectious bacteria are present. Without antibiotic treatment, acute otitis of bacterial origin can cause perforation of the eardrum, with drainage of pus from the ear. Although the eardrum may heal after the infection has resolved, permanent damage to the middle ear and/or the inner ear can sometimes result from infections of this severity. Chronic otitis media is typically caused by a form of chronic mastoiditis and results in a chronic infection of the middle ear and mastoid cavity. Because the mastoid bone is involved, treatment with antibiotics administered by traditional routes of administration (i.v., i.m., oral, etc.) sometimes does not remove the infection from the bone and surgical removal of the infected mastoid bone may be necessary. A common complication associated with chronic otitis and mastoiditis is cholesteatoma. A cholesteatoma is a soft tissue sac that emanates from the eardrum and grows back into the middle ear or mastoid, thereby creating a mass of progressively increasing size which can destroy or damage the bones of the middle ear, the inner ear, the facial nerve and/or portions of the brain. Thus, the various forms of otitis can be very serious if left untreated. As new interventional or surgical techniques are developed for treatment of Eustachian tube dysfunction and/or otitis media, it may be desirable to place drug eluting or non-drug eluting stents within the Eustachian tube. Apart from the drug eluting sheath described by Gopferich et al., various other types of implantable drug delivery devices have been proposed for use in the nose and/or paranasal sinuses. For example, U.S. Pat. No. 3,948,254 (Zaffaroni) describes implantable drug delivery reservoirs having microporous walls. The reservoir may be formed of a solid drug carrier that is permeable to passage of the drug and the rate of passage of the drug through the microporous wall may be slower than the rate at which the drug passes through the solid drug carrier that forms the reservoir. Zaffaroni also describes a number of applications for the implantable drug delivery devices including placement in a nasal passage. Specifically, Zaffaroni claims a nasal delivery device for dispensing a drug within a nasal passage at a controlled rate wherein the nasal device is comprised of (a) a wall defining the device dimensioned for insertion and placement within a nasal passage, with the wall formed of a nasal acceptable microporous material, (b) a reservoir surrounded by the wall and comprised of a solid carrier permeable to drug and containing drug in an amount sufficient for the device to meter it at a continuous and controlled rate for a prolonged period of time from the device, (c) a liquid medium permeable to the passage of drug by diffusion charged in the micropores, and (d) wherein the device releases drug when in a nasal environment by passage of drug from the carrier and through the liquid to the exterior of the device to produce a useful result. The entire disclosure of U.S. Pat. No. 3,948,254 (Zaffaroni) is expressly incorporated herein by reference.
Other publications have also reported that introduction of drugs directly into the paranasal sinuses is effective in the treatment of sinusitis. See, Tarasov, D. I., et al., Application of Drugs Based on Polymers in the Treatment of Acute and Chronic Maxillary Sinusitis, Vestn Otorinolaringol. Vol. 6, Pages 45-7 (1978). Also, R. Deutschmann, et al., A Contribution to the Topical Treatment of [Maxillary] Sinusitis Preliminary Communication, Stomat. DDR 26 (1976), 585-592 describes the placement of a resorbable drug delivery depot within the maxillary sinus for the purposes of eluting drugs, specifically Chloramphenicol. In this clinical series a water soluble gelatin was used as carrier and was mixed with the drug prior to application and introduced as a mass into the sinus. Since the substance had little mechanical integrity and dissolved in a relatively short timeframe, to achieve a therapeutic effect, the author suggested that it must be instilled every 2 to 3 days. An alternative to gelatin could be a sponge loaded with the therapeutic substance as suggested in U.S. Pat. No. 6,398,758 (Jacobsen, et al.). In this patent directed at delivering a sustained release device against the wall of a blood vessel, a hollow cylindrical sponge is loaded with drug and pressed against the wall. This allows the drug to contact the wall while sustaining blood flow within the center of the lumen. Further, a skin is provided to direct the drug into the walls of the blood vessel and prevent drug from flowing into the lumen. While sponges loaded with drug at the time of their application do permit some degree of sustained release, the time required to load them also correlates closely the time over which they will elute substance. Thus, if delivery is required for a longer period of time additional mechanisms must be employed to regulate their release.
There are also several examples in the patent literature where various sustained release mechanisms have generally been proposed using systems with pre-incorporated drugs into matrices or polymers. These include U.S. Pat. No. 3,948,254 (Zafferoni), US 2003/0185872A2 (Kochinke), WO 92/15286 (Shikani), and U.S. Pat. No. 5,512,055 (Domb, et al.). In general, these references discuss various materials and structures that may be used to construct sustained drug delivery vehicles and provide a good overview of the state of sustained drug delivery art. While helpful in laying out certain materials and schemes for creating sustained release systems for drugs, each of these references, however, do not describe specific methods, means or structures which would permit them to be easily adapted for intended uses that are targeted in this application.
Other examples of implantable drug delivery devices include those described in U.S. Pat. Nos. 3,993,073; 4,217,898; 5,304,123; 6,042,561; 6,183,461; 6,780,168 and 6,783,522, the entire disclosure of each such patent being expressly incorporated herein by reference.
There remains a need in the art for the development of new devices and methods for delivering drugs and other therapeutic or diagnostic substances over a sustained period of time into paranasal sinuses, Eustachian tubes, middle ear and/or other locations within the body for the treatment of sinusitis, otitis or other diseases and disorders.